Pregnancy overall was associated with disrupted sleep as indicated by more time awake after sleep onset and a higher microarousal index on polysomnography, both significant compared with women who weren't pregnant, Sirimon Reutrakul, MD, of Rush University Medical Center in Chicago, and colleagues found.

Among pregnant women, though, gestational diabetes was associated with 6.60-fold elevated likelihood of OSA after adjustment for pre-pregnancy body mass index, the researchers reported online in the Journal of Clinical Endocrinology & Metabolism.

Their total sleep time was also lower by about an hour a night and apnea-hypopnea index was higher than expectant mothers without gestational diabetes.

While the study couldn't prove causality or its direction, the associations weren't explained by gestational weight gain.

One prior study has shown better pregnancy outcomes with continuous positive airway pressure (CPAP) treatment in women with hypertension and chronic snoring, but there are no data on CPAP use in women with gestational diabetes.

"As most of our gestational diabetes mellitus participants with OSA had only mild OSA, it remains to be proven if CPAP treatment will affect glucose metabolism and pregnancy outcomes," Reutrakul's group cautioned.

Meanwhile, clinicians should watch for OSA in women diagnosed with gestational diabetes, especially in the presence of other risk factors like obesity and hypertension, they recommended.

"Conversely, for women with an established diagnosis of OSA who become pregnant, consideration should be given to early screening for gestational diabetes," they added.

Their observational case-control study analyzed polysomnography results of 15 nonpregnant women without diabetes, 15 pregnant women with normal glucose tolerance, and 15 pregnant women with gestational diabetes -- all matched for age and race or ethnicity.

The pregnant women were studied during the late second to early third trimester.

Those without gestational diabetes had more disrupted sleep than women who weren't pregnant, as indicated by:

After adjusting for that factor, a higher microarousal index correlated with higher hemoglobin A1c. Both microarousal and elevated oxygen desaturation index were associated with higher fasting glucose levels.

The researchers pointed out that the study avoided confounding from abnormal circadian timing by timing the polysomnography test to the "usual sleep habits of the participants to increase relevance to real-life conditions."

But the lack of data on a wide range of other potential confounders was a limitation, along with the observational design and small sample size.

The study was supported by the ResMed Foundation, the Diabetes Research Training Center at the University of Chicago, the National Institute on Aging, the Blum-Kovler Family Foundation, and the National Institutes of Health's National Center For Advancing Translational Sciences.

Reutrakul reported having no conflicts of interest to disclose. A co-author reported relationships with Philips/Respironics, the ResMed Foundation and Amylin/Lilly, Pfizer, Viropharma, the journal SLEEP, and the law firm of Lamson, Dugan and Murray as an expert witness.

Reviewed by F. Perry Wilson, MD, MSCE Instructor of Medicine, Perelman School of Medicine at the University of Pennsylvania and Dorothy Caputo, MA, BSN, RN, Nurse Planner